This invention relates to a process for surface treatment including various treatments such as etching, modification, cleaning, or impurity doping of the surface of semiconductor, metal or insulating material (which will be hereinafter referred to generally as "workpiece") or deposition of a film on the surface, and more particularly to a process for surface treatment suitable for precise etching or modification of the surface of a semiconductor material or film deposition thereon.
Heretofore, a gas plasma or ion beam has been used in the etching treatment in the production of semiconductor devices. That is, the etching treatment has been carried out by allowing ions or electrons from a plasma, when the plasma is used, to hit the surface of a workpiece, or ions, when an ion beam is used, to hit the surface of a workpiece. Phenomena that these electrically charged particles hit the surface of a workpiece and also the problems encountered in the production of semiconductor devices are discussed in Dry Process Symposium Proceeding (1985) V5, 132P. That is, the etching treatment carried out by allowing the electrically charged particles to hit the surface of the workpiece has such a problem that the surface of the workpiece is electrically charged, and the resulting insulating film is deteriorated. It has been found that the problem occurs not only in case of the etching treatment, but also in case of the surface treatments using the electrically charged particles, such as cleaning or impurity doping of the surface, or modification of the surface or deposition of a film on the surface.
With recent demands such as a considerably higher integration density for the semiconductor devices and much smaller dimensions for the transistors, etc., the influence of the electrical charging of the surface of a workpiece by the electrically charged particles cannot be disregarded, and it is indispensable to prevent the influence of electrical charging by the electrically charged particles to make the dimensions of various semiconductor devices much smaller.